Elementary got so unexpectedly dark in the episode "Poison Pen" that it's more along the lines of Law & Order: SVU and filled with moral dilemmas. While some episodes are more Sherlock/Joan-centered, this one was mostly all about the case.

Fire in the Hole

It all starts when Joan joins Sherlock at the boxing ring, watching him "fight dirty," according to her. He gets a call from "Mistress" about a dead body, and the two head to a home, where the mistress is there with her ... well, slave ... in a latex outfit -- and dead.

But first, about this mistress, who we met once, took up Sherlock as they chatted about the torture devices throughout history and stayed in touch. Would kind of like to be a fly on the wall for that conversation.

Anyway, the older man found dead is the CEO of a big financial consulting group. Mistress just got to the house and found him dead. Theories are tossed about as to the cause of death. Was he too excited for what was to come and had a heart attack? Did he overmedicate?

Nope -- Sherlock deducts with a glass of bourbon and lighting it after pouring some on the table that the man was poisoned.

The Pleasure Parlor

The man's suit leads Joan and Sherlock to a sex shop that would only sell the XXL size the man had worn -- the Pleasure Parlor. The owner there isn't too forthcoming with the details of the customer as he has a job to protect the privacy of people who come into his store.

Getting a subpoena to get fingerprints off the other latex suits would've taken far too long, so thanks to some clever coercion by Bell, the shop owner reveals that the person who bought the suit paid with cash from the store's ATM. Bingo -- there's photographic evidence.

Except the man who's then brought in, one of Titus' employees, is just a tool, and not a killer, who just put his boss in the suit for no real reason other than being "a greedy jerk with questionable judgment." His words.

True Identity

The rest of the victim's family have arrived at the home after staying at their other house for the night, so Sherlock and Watson pay a visit. The wife of three years is actually a stepmom after the boys' mother died of cancer. Their nanny also arrives after hearing the news. When she and Sherlock greet each other, it's clear there's something about her that makes him pause.

He reveals to Joan that the nanny is not who she's claiming to be, identity wise. She's actually a woman who, when she was a teen in 1991 was accused of killing her father -- with the same substance that was used to killed Titus.

When Abigail is brought to the station, she admits to her real identity, but not either crime, although when Titus was killed, she was home alone. No alibi. She said the media back then had ruined her life, and being accused of this murder means it'll happen again. Back then, she had run away, changed her identity and gotten plastic surgery so she could never be recognized again.

Yet Sherlock did.

Shawn Holmes

He reveals to Abigail that he recognized her by her voice, but in reality, he had recognized her by the tattoo. It turns out that when Sherlock was 15, he was fascinated by Abigail's trial and story that he wrote to her while she was in prison -- and she wrote back. Back then, he went by Shawn. Shawn Holmes!

After hearing her at the station, he's certain she didn't kill Titus, even though he's quite certain she did kill her father all those years ago. She's being framed.

He goes to see her and tells her all of this, and she remembers being followed by a van recently. Being paranoid, she smartly wrote down the license plate, which is then tracked to a private investigator -- hired by the wife, initially to investigate all the women in her husband's life to find out if he was having an affair.

Hunting for the Truth

The wife knew everything since the PI uncovered the nanny's secret. And it makes her highly suspicious that she wouldn't come forth with the information, knowing that a possible killer was with her stepkids daily.

So where was she the night of the murder? She had gone to see a doctor to get the poison because she had thought about killing her husband! So let's get this straight: She could not have killed her husband because she was too busy planning to do so. Ugh!

So now the suspicions shift to the older kid, who is poised to have access to his trust. But not so fast: Graham shows Sherlock and Joan video he shot of Abigail arguing with Titus about his tablet that had gone missing. He thought she stole it. It was such a non-important issue that Abigail had forgotten about it since he had apologized for overreacting.

Coming to a Close

So now we have two highly suspicious people: Graham and Abigail. The clue is in the missing tablet, which is not in the drawer in Titus' locked case. It's actually in a vent that's not really a vent but supposed to make it look like one to hide such things as hiding tablets!

So what's in this suddenly important tablet? The fact that Titus was sexually abusing his own son. Didn't see that one coming.

When he's brought into questioning, everyone tries to get him to confess, that he poisoned his father for what he was doing to him. He looks extremely guilty, but is not budging. Abigail, instead, overcome with her own guilt and grief on the matter -- this had been going on right under her nose -- confesses to the murder.

She won't turn back and wants to go down for this because of what she did all those years ago. She feels she deserves this, that she brought this on herself. Just because Graham did what he did, doesn't mean he should have to pay. It's almost the mirror image of what happened to the both of them -- both being abused and ultimately taking matters into their own hands to stop the pain.

Sherlock meets with Graham, saying he's keeping an eye on him to make sure he doesn't take extreme measures like this again. He probably knows that it won't. Besides, the real reason for the meeting is to tell Graham that if he ever needs to talk to someone about what happened to him, that he can call Sherlock.